Many New Jersey residents can't turn on the lights, and they even have to be careful about taking a drink. Gov. Chris Christie said yesterday that a dozen water utilities have issued advisories to boil water.

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It's part of a wider campaign to warn people of the many risks after the storm. Public health officials are urging people to protect themselves from threats in the air, and even in their refrigerators.NPR's Rob Stein reports.

ROB STEIN, BYLINE: As millions of people try to put their lives back together, there are potential risks all around them. Tina Tan, of the New Jersey Department of Health, says the most obvious threat is the floodwaters themselves. In many places, the water could be a toxic stew.

TINA TAN: Floodwaters potentially could contain mixtures of a variety of chemicals such as pesticides, paint, gasoline; you know, other things, for example, that you might store in your garage or your basement, that might actually get all flooded out.

STEIN: And in several places, sewage-treatment plants have been paralyzed by fires or flooding. In these areas, bacteria and other pathogens in the water, could make people sick.

TAN: That kind of shows up as nausea, vomiting, diarrhea, and other symptoms related to gastrointestinal illnesses.

STEIN: These infections can be serious for babies, the elderly, and people who are already sick. Contaminated floodwater rarely causes the kind of widespread disease outbreaks that can occur in less-developed countries.

TAN: In our recent history, we haven't really seen a lot of outbreaks that are associated with floods, in general, here. But that doesn't mean that we still shouldn't take caution.

STEIN: So officials are urging people to have as little contact with floodwaters as possible; and if they have no choice, to wear protective gear like boots, gloves and goggles.

TAN: If, for some reason, you come into contact with the floodwater - that there's floodwater that touches the skin, wash your hands with soap and clean water very often, just to clean yourself of any - sort of potential contaminants.

STEIN: In places where drinking water supplies may be contaminated, people have to boil their water for at least a minute, before it's safe to drink. Dan Kass, of the New York City Health Department, says that's one thing city residents don't have to worry about.

DAN KASS: The genius of the New York City water supply is that we have ample reservoirs located away from the city, that are groundwater based. [POST-BROADCAST CORRECTION: Kass misspoke; the reservoirs are not groundwater based.]

STEIN: The water also flows downhill, so no electricity is needed to pump it in. And while some people may wonder whether the flooded subway system may fill the streets with fleeing rats, officials say that's not a problem, either. There are far fewer rats down there than people think. And many of those, there, probably drowned. A much bigger worry is what might be in the air. Kass says one of the most common killers, after a big disaster, is carbon monoxide poisoning among people misusing generators.

KASS: They can't be used indoors. They have to be properly vented. And while people are desperate for power, they sometimes take shortcuts or don't fully understand the risks.

STEIN: Aside from the water and air, other dangers may be lurking. Downed wires can electrocute people. People needing dialysis, or other life-sustaining care, often can't get what they need. Other people lose their prescription drugs, or run out.

KASS: They may not have critical belongings that they need, not only for - sort of physical health, but for mental health. And so that's something that's a huge challenge, for people.

STEIN: And there are other risks for people who are still home. Tom Frieden, who heads the Centers for Disease Control and Prevention, says food poisoning is a common problem after disasters. That's what happened when he was health commissioner in New York City.

DR. TOM FRIEDEN: In 2003, there was a long blackout in August; and we saw a significant increase in foodborne illness, in the days after.

STEIN: Frieden says food in the refrigerator only stays cold for about four to six hours, without power. Food in the freezer holds for maybe 24 to 48 hours. After that, don't risk it.

FRIEDEN: Bottom line is: If in doubt, throw it out.

STEIN: Once the waters recede, mold could start growing in a lot of homes, triggering allergic reactions and asthma attacks. So people will have to clean up and dry out what they can and tear out and throw out the rest.

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